Copy rotation is twisting bone
It's not working in world space because the target of your copy rotation constraint has a different world space orientation that the foot that is copying that rotation.  Your IK bone is pointed at the ceiling, while your foot bone is pointed at the toe.

If you want to use world space copy rotation, give each bone the exact same orientation.  The easiest way to do this is to make your IK bone a duplicate of the foot bone (but with the parent cleared of course.)